US3795903A
Expired / Lapsed
US
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Modified phase encoding
Assignee: International Business Machines Corp
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Filing: 1972-09-29
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Granted: 1974-03-05
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Expires: 1992-09-29
Abstract
Abstract An encoding and decoding technique for detecting loss of phase and/or bit sync, and resynchronizing following an error. Both detection and resynchronization are accomplished on a per character basis. With seven bits being used per character, the bits making up each character are phase encoded in a conventional manner. For defining each character, an additional 1/2 bit time is added between bits 7 and 1 and encoded such that a corrective flux reversal may occur at 1/2 T (where T equals the normal intracharacter bit time), a transition must not occur at T (normal data time), and the 1 bit of the next character must occur at 1 1/2 T. Digital data separation is used to define corrective flux reversals and data bits, and any flux transitions outside the limits defined are considered errors. During decoding, the data separation logic is resynchronized on each detected data transition by the sync signal. With this method, if either phase or bit sync is lost within any character, an error condition will be detected at least before bit 1 of the next character.
Inventors
- 👤 R Lindsey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:59
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/18
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
69 words
A method of recording a block of digital data for facilitating error checking during decoding, said method comprising phase encoding said data on a per segment basis according to a defined format wherein 1) each data bit making up a segment is separated by one bit time, and 2) a flux reversal between segments will not occur at one bit time following the last data bit of each segment.
Claim 2
Independent Claim
69 words
A method of recording a block of digital data for facilitating error checking during decoding, said method comprising phase encoding said data on a per segment basis according to a defined format wherein 1) each data bit making up a segment is separated by one bit time, and 2) a flux reversal between segments will not occur at one bit time following the last data bit of each segment.
Claim 3
Dependent Claim
30 words
A method according to claim 1 wherein 0aid phase encoding according to a defined format includes adding a number of fractional bit times to each segment for distinguishing each segment.
Claim 4
Dependent Claim
28 words
A method according to claim 2 wherein said fractional bit times added to each segment are added at the end of the last data bit of each segment.
Claim 5
Dependent Claim
39 words
A method according to claim 3 wherein said phase encoding according to a defined format includes causing any flux reversal between segments to occur at one of said fractional bit times following the last data bit of each segment.
Claim 6
Dependent Claim
25 words
A method according to claim 4 wherein said phase encoding according to a defined format includes separating each segment by one and one-half bit times.
Claim 7
Dependent Claim
25 words
A method according to claim 5 wherein said phase encoding on a per segement basis includes phase encoding said data on a per character basis.
Claim 8
Dependent Claim
14 words
A method according to claim 5 wherein said data is recorded serially by bit.
Claim 9
Independent Claim
147 words
A method of detecting errors in recorded digital data, phase encoded on a per segment basis according to a defined format wherein 1) each data bit making up each segment is to be separated by one bit time, and 2) a flux reversal between segments is not to occur at one bit time following the last data bit of each segment, said method comprising: a. reading said recorded data; b. synchronizing the timing of a first set of comparative conditions upon reading a flux reversal for each data bit other than the last data bit of each segment in said recorded data; c. synchronizing the timing of a second set of comparative conditions upon reading a flux reversal for said last data bit of each segment in said recorded data; and d. comparing said first and second conditions with other flux reversals read from said recorded data.
Claim 10
Independent Claim
147 words
A method of detecting errors in recorded digital data, phase encoded on a per segment basis according to a defined format wherein 1) each data bit making up each segment is to be separated by one bit time, and 2) a flux reversal between segments is not to occur at one bit time following the last data bit of each segment, said method comprising: a. reading said recorded data; b. synchronizing the timing of a first set of comparative conditions upon reading a flux reversal for each data bit other than the last data bit of each segment in said recorded data; c. synchronizing the timing of a second set of comparative conditions upon reading a flux reversal for said last data bit of each segment in said recorded data; and d. comparing said first and second conditions with other flux reversals read from said recorded data.
Claim 11
Dependent Claim
28 words
A method according to claim 8 wherein said synchronizing the timing of said first and second conditions includes generating a sync signal when a data bit is read.
Claim 12
Dependent Claim
20 words
A method according to claim 9 wherein said first and second conditions comprise signals generated according to said defined format.
Claim 13
Dependent Claim
31 words
A method according to claim 10 further including signalling an error condition when said first and second conditions do not correspond to said other flux reversals read from said recorded data.
Claim 14
Dependent Claim
15 words
A method according to claim 11 further including counting data bits making up said segments.
Claim 15
Dependent Claim
37 words
A method according to claim 12 further including resynchronizing the timing of one of said first and second conditions, according to the bit counted during said counting, when a flux reversal is read from said recorded data.
Claim 16
Dependent Claim
35 words
A method according to claim 12 further including resynchronizing the timing, when said error condition is signalled, of one of said first and second conditions, when a flux reversal is read from said recorded data.
Claim 17
Dependent Claim
32 words
A method according to claim 14 further including inhibiting any signalling of any additional error conditions for subsequent errors in a segment until a complete segment has been read without an error.
Claim 18
Independent Claim
127 words
A method of recording a block of digital data, decoding said recorded data, and detecting format errors in said recorded data, said method comprising: a. phase encoding said data on a per segment basis according to a defined format wherein 1) each data bit making up each segment is separated by one bit time, and 2) a flux reversal between segments will not occur at one bit time following the last data bit of each segment; b. decoding said phase encoded data; c. synchronizing a first set of comparative conditions for intrasegment timing during said decoding; d. synchronizing a second set of comparative conditions for intersegment timing during said decoding; and e. comparing said first and second conditions correspondingly with said phase encoded data during said decoding.
Claim 19
Independent Claim
127 words
A method of recording a block of digital data, decoding said recorded data, and detecting format errors in said recorded data, said method comprising: a. phase encoding said data on a per segment basis according to a defined format wherein 1) each data bit making up each segment is separated by one bit time, and 2) a flux reversal between segments will not occur at one bit time following the last data bit of each segment; b. decoding said phase encoded data; c. synchronizing a first set of comparative conditions for intrasegment timing during said decoding; d. synchronizing a second set of comparative conditions for intersegment timing during said decoding; and e. comparing said first and second conditions correspondingly with said phase encoded data during said decoding.
Claim 20
Dependent Claim
30 words
A method according to claim 16 wherein said phase encoding according to a defined format includes adding a number of fractional bit times to each segment for distinguishing each segment.
Claim 21
Dependent Claim
28 words
A method according to claim 17 wherein said fractional bit times added to each segment are added at the end of the last data bit of each segment.
Claim 22
Dependent Claim
39 words
A method according to claim 18 wherein said phase encoding according to a defined format includes causing any flux reversal between segments to occur at one of said fractional bit times following the last data bit of each segment.
Claim 23
Dependent Claim
25 words
A method according to claim 19 wherein said phase encoding according to a defined format includes separating each segment by one and one-half bit times.
Claim 24
Dependent Claim
28 words
A method according to claim 16 wherein said synchronizing the timing of said first and second conditions includes generating a sync signal when a data bit is decoded.
Claim 25
Dependent Claim
20 words
A method according to claim 21 wherein said first and second conditions comprise signals generated according to said defined format.
Claim 26
Dependent Claim
49 words
A method according to claim 22 wherein the directions of flux reversals for the last data bit of one segment and the first data bit of a following segment are determined for determining whether a flux reversal is to occur before the first data bit of said following segment.
Claim 27
Dependent Claim
28 words
A method according to claim 23 further including signalling an error condition when said first and second conditions do not correspond to other flux reversals during said decoding.
Claim 28
Dependent Claim
15 words
A method according to claim 24 further including counting data bits making up said segments.
Claim 29
Dependent Claim
33 words
A method according to claim 25 further including resynchronizing said timing of one of said first and second conditions, according to the bit counted during said counting, when a flux reversal is decoded.
Claim 30
Dependent Claim
31 words
A method according to claim 25 further including resynchronizing said timing, when said error condition is signalled, of one of said first and second conditions, when a flux reversal is decoded.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |